From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <606456fcdc17ce997666a1895d86f9ba@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
From: "Russ Cox" <rsc@plan9.bell-labs.com>
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Subject: [9fans] kernel config changes
Date: Fri, 13 Dec 2002 03:32:49 -0500
Topicbox-Message-UUID: 332f236a-eacb-11e9-9e20-41e7f4b1d025

There is a new kernel config file section called "bootdir" that lists
the files to be placed in #//boot.  There are no binaries in #/ itself
anymore.

A typical bootdir section might look like

	bootdir
		bootpcdisk.out boot
		/386/bin/ip/ipconfig
		/386/bin/auth/factotum
		/386/bin/disk/kfs
		/386/bin/cfs

which says that /boot will contain four files: boot, ipconfig,
factotum, kfs, and cfs, copied from the paths listed.

The kernels have always special cased boot$CONF.out to get it listed
as /boot.  It is now /boot/boot, and no longer a special case.

Now that everything is in /boot, initcode had to change for all the
kernels; /boot/boot itself had to change to exec /boot/ipconfig
(instead of /ipconfig), etc.  Finally, auth_getkey changed.  It looks
for /factotum and then /boot/factotum, to deal with either type of
kernel.

The boot file /386/bin/ip/ipconfig (e.g.) turns into
_386_bin_ip_ipconfig.root.s and then _386_bin_ip_ipconfig.root.8.
It's a bit of an ugly name, but mk clean will get rid of them.  You
could imagine just using the last path element, but that might lead to
weird build inconsistencies if kernels were using two different files
with the same last element.  One unfortunate consequence of the big
name is that _386_bin_auth_factotum.root.s is too long for the current
file servers to deal with.  You could use lnfs to get around this, but
I didn't want to require lnfs for the kernel build, so we have a rule
in portmkfile that copies factotum and ipconfig to factotum.hack and
ipconfig.hack and then the bootdir section actually looks like:

	bootdir
		bootpcdisk.out boot
		ipconfig.hack ipconfig
		factotum.hack factotum
		/386/bin/disk/kfs
		/386/bin/cfs

sadly.  That will go away when we get long file names.

The pc initcode is also changed.  Whereas before it used to do

	exec("/boot", ["boot", 0]);

in hand-coded assembly (pc/initcode.s), it now does

	open("#c/cons", OREAD);
	open("#c/cons", OWRITE);
	open("#c/cons", OWRITE);
	bind("#c", "/dev", MAFTER);
	bind("#ec", "/env", MAFTER);
	bind("#e", "/env", MCREATE|MAFTER);
	bind("#s", "/srv", MREPL|MCREATE);
	execl("/boot/boot", "/boot/boot", 0);

in C (port/initcode.c).  The point is to set up enough of a namespace
that /boot/boot can be a shell script.  Eventually the other
architectures should change too, though it's not urgent.  If someone
wants to do the bitsy, send me mail and I'll let you know what it took
to get one of the old undistributed mips kernels changed over.  (The
compiler setup is similar.)

As a much bigger example, I built a kernel called pcext the other
night.  It uses rx and trampoline to connect through a Plan 9 gateway
machine to the root file server.  It uses this bootdir:

	bootdir
		bootext boot
		/386/bin/rc
		/rc/lib/rcmain
		/386/bin/bind
		/386/bin/cat
		/386/bin/cp
		/386/bin/echo
		/386/bin/mount
		/386/bin/sleep
		factotum.hack factotum
		/386/bin/ip/ipconfig
		/386/bin/cfs
		/386/bin/aux/srvthru

(and does require lnfs to build).

Srvthru is the obvious program -- it connects to rx,
authenticates, starts trampoline to the real file server,
and then optionally pushes cfs onto the connection.

The point is that bootext is a shell script, which
makes it easier to tweak than when /boot was a
binary building out of /sys/src/9/boot.

	#!/boot/rc -m /boot/rcmain

	cd /boot
	cp '#r/rtc' '#c/time'
	bind -a /boot /bin
	bind -a '#I' /net
	bind -a '#l0' /net
	bind -a '#S' /dev
	bind '#p' /proc
	bind '#d' /fd
	bind -a /boot /
	ipconfig
	echo 'authdom=cs.bell-labs.com auth=204.178.31.3' >>/net/ndb
	factotum -sfactotum -u -a 204.178.31.3
	cargs=()
	if(~ $#cfs 1 && ! ~ $cfs off)
		cargs=(-c $cfs)
	srvthru $cargs tcp!204.178.31.2!17009 il!emelie!9fs boot emelie
	mount -c /srv/boot /root
	bind -ac /root /
	bind -c /root/mnt /mnt
	mount -a '#s/factotum' /mnt
	rootdir=/root
	rootspec=''
	/386/init -t
	/boot/rc -m/boot/rcmain -i	# in case init fails

It takes care of everything /boot traditionally
does, using srvthru as the way to establish /srv/boot
(and also /srv/emelie, just for kicks).

Russ